The move came as Venezuelan President Hugo Chavez accused his US counterpart George W Bush of genocide and said he should be jailed.
The US sanctions ban arms sales and technology transfers to Venezuela, saying Mr Chavez's government has not done enough to combat terrorism, according to a State Department official.
"We are certifying to Congress that Venezuela is not fully cooperating with US anti-terrorism efforts," said spokesman Eric Watnik, speaking to AFP.
"US sales and licenses for the export of defence articles and services to Venezuela, including the retransfer of defence articles, will not be permitted," he said.
Mr Chavez, in London on a private visit, reiterated his threat to cut Venezuelan oil exports to the US and warned that oil prices could soar above US$100 a barrel if war is declared against Iran over its disputed nuclear program. He said any such attack would be "madness".
Bush "genocidal": Chavez
Mr Chavez, whose short visit to the UK does not include a meeting with Prime Minister Tony Blair or any government members, also launched into another attack on his US counterpart.
When one BBC journalist likened him to the US leader, he erupted in anger, describing Mr Bush as the biggest genocidal figure alive, and said he should be imprisoned by an international court.
"Have I invaded any country? Have Venezuelans invaded anything? Have we bombarded a city? Have we had a coup d'etat? Have we used the CIA to kill a president? Have we protected terrorists in Venezuela? That's Bush!" he said, speaking at a joint press conference with London Mayor Ken Livingstone.
The Bush administration has thorny relations with the outspoken leftist Venezuelan president, whose country is the fourth-largest supplier of oil to the US.
Washington claims the Venezuela leadership has restricted the freedom of the press and harassed the opposition.
In return, Mr Chavez often criticises Mr Bush for the Iraq war and has openly called the US leader a "coward" and a "murderer".
The sanctions, announced on Monday, amplify US moves to militarily isolate Venezuela. In January, Washington intervened to prohibit the sale of US arms or military technology to Venezuela by third countries, such as Spain and Brazil.
The US has in recent months become increasingly vocal in its opposition to Chavez and his government.
Secretary of State Condoleezza Rice has cited Venezuela as the region's biggest problem and has called on US allies to mount a united front in dealing with it.
The US intelligence chief, John Negroponte, has accused Chavez of seeking closer ties with Iran and North Korea, two countries on Bush's "axis of evil" list. The Venezuelan government rejects the US accusations.